Highly reliable and radiation tolerant electronic devices have become more and more important for automobile, Internet-Of-Thing and space applications. Electronic devices, such as transistors, can degrade in performance after operating for a period of time.
Transistors degrade mostly due to trapping of carriers (i.e., electrons and hole) and atomic bond ruptures in the gate dielectrics of the transistors. Such degradations are usually reversible. The damages can be repaired by annealing the transistors under high temperatures. A micro-heater can be built in close proximity to the transistors to raise the local temperature of the transistors for a short time. The temperatures of the transistors can be raised for a period of time that is enough to repair the damages in the transistors and not cause damages to other parts of the integrated circuit chip. Therefore, periodic on-chip annealing of transistors will extend their lifetime.
Fin field-effect transistors (finFETs) comprise a narrow source-channel-drain region in a fin-shaped structure on a substrate and a gate over the channel. Activation of the gate, source, and drain facilitates current drivability in the channel between the source and the drain. The demand for increased density of transistors in integrated circuit chips requires reducing the channel length of finFETs. If the channel length is reduced to be shorter than an operational limit, undesirable results such as short channel effects (e.g., source-to-drain leakage and drain-induced barrier lowering) can happen. Highly doped anti-punch-through implants under the fins of the finFETs can reduce such short-channel effects. Anti-punch-through implants are formed by ion implantation through the fins or other methods.
Current flowing through resistors, such as the anti-punch-through implants, encounters resistance, and some electrical energy is transformed into thermal energy. The heat generated is directly proportional to the current. Lower resistance results in higher current and increased generation of heat.
It would be advantageous to find ways to reduce degradation in transistors and extend their life by annealing the transistors with heat generated from on-chip anti-punch-through implants.